<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title></title>
        <style>
            h1::before{
                content: url(/imgs/250.png);
            }
            h1::after{
                content: url(/imgs/resou.png);
            }
        </style>
    </head>
    <body>
        <h1>this is heading</h1>     
        <p>The :before pseudo-element inserts content before an element.</p>   
        <h1>this is heading</h1>  
        <p><b>注意:</b>仅当 !DOCTYPE 已经声明 IE8 支持这个内容属性</p>
    </body>
</html>